The compounds N'-benzylidene-N-methylpyrazine-2-carbohydrazide, C13H12N4O, (IIa), N'-(2-methoxybenzylidene)-N-methylpyrazine-2-carbohydrazide, C14H14N4O2, (IIb), N'-(4-cyanobenzylidene)-N-methylpyrazine-2-carbohydrazide dihydrate, C14H11N5O·2H2O, (IIc), N-methyl-N'-(2-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H11N5O3, (IId), and N-methyl-N'-(4-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H11N5O3, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55-78°. These methylated pyrazine-2-carbohydrazides have supramolecular structures which are formed by weak C-H···O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π-π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0-6°.